I started using LDAP about 5 months ago (or so I forget) I needed to because the project called for it. Any ways the benefits in my opinion are:

It's very good for long term storage, if you plan on just adding and leaving data it's great for it. You see LDAP is designed to be very fast at retrieving data but not at updating it. So it's best once in to be forever in. This isn't saying you can't or shouldn't but you want to limit the amount you do, especially on a large scale.

LDAP stores in a directory structure i.e.
Top entry
next entry
another entry
second entry

Look how your C: drive looks and you'll see how it stores data.
This is a plus when storing data in different category and section etc.. It helps in separating items, which in turn makes it easier to search on and retrive.

The most obvious difference between relational and LDAP is LDAP is in a tree structure and a relational database isn't. In a relational DB you search across and down, in LDAP you search down.

I know I'm not thinking of everything that is good about it, but in my opinion it depends on what you'll need it for.